From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Comparison of brake tests between the E.A.C. high-speed servo and Hispano systems in North Devon.
| Identifier | ExFiles\Box 22\1\ Scan093 | |
| Date | 7th February 1924 guessed | |
| BRAKE TESTS - NORTH DEVON+ E.A.C. HIGH SPEED SERVE AND HISPANO SYSTEM COMPARED. Gradients up to 1 in 4 measured with gradiometer. Steeper - local intelligence obtained. | OBSERVATION. | EAC. (Cast iron servo linings.) | HISPANO SUIZA. | |---|---|---| | Forward braking. | Will hold on 1 in 4 - considerable pedal pressure. | Will hold on 1 in 4 - reasonable pedal pressure | | Backward braking. | Will hold on 1 in 4½ with about the same pressure as is required to hold the Hispano on 1 in 7½. | Hold on 1 in 4½. Max. personal effort required. | | Max, temperature attained by servo drum. | 500° - 550°C. | 50° - 60°C | | Ordinary touring temp: attained by servo, no severe gradients. | Below 200°C | Barely warm. | | Adjustments required throughout tests. | None. | None. | | Change in functioning of brakes due to tests. | Not appreciable. | Not appreciabl.e | | Objectionable features observed during tests. | Rather too much pedal pressure required for comfortable continued application down long hills. Servo jaggers slightly when warm and applied severely. Smoke and smell from servo when very hot. Sogging when applied suddenly and occasional front axle jaggers. | Far too much pedal pressure required for backward braking on severe gradients | | ||